Pressure responsive device



June 27, 1944. DQNALDSQN 2,352,312

PRESSURE RESPONS IVE DEVICE Filed Dec. 51, 1941 e Sheets-Sheet; 1

94 v NTO 1 19k ATTORNEY June 27, 1944. R. R. DONALDSON PRESSURERESPONSIVE DEVICE 6 Sheets-Shet 2 Filed Dec. 31, 1941 2 h 3 7. 6 3 8 5 mM wqflpw 5 2 M 1... ..r 0 n 5 h 3/1 0 6 B Q fi \nm 7 8 pawl lit. 4 M\kW/d X3444 ATTORNEY June 27, 1944. R, R, DO'NALDSON 2,352,312

PRESSURE RESPONS IVE DEVICE Filed Dec. 31, 1941 6 Sheets-Sheet 3 852mid-going ifiapu/se of comp cried cur' Compresrd air in ai" cansfzznl'arwune ressur'e P P from vebsiel e a (low przssum pressure 5 am vessel(/ziqh Pressure) F I i I VI 2Q I z F R [L2- 4 F, c 110 186 y- C 120 I IA l 12 98 FM l l IIIIIHII IIHHHHIH IHIHI IIHIII IHIIIHJH June 27, 1944.R DONALDSON 2,352,312

PRESSURE RESPONS IVE. DEVICE Filed Dec. 31, 1941 6 Sheets-Sheet 4 M\ i66 Mel 33 29 Z? I r= l W ATTORNEY PRESSURE RESPONS IVE DEVICE FiledDec.' 3]., 1941 6 Sheets-Sheet 5 ATTORNEY June 27, 1944. R. R. DONALDSON2,352,312

PRESSURE RESPONS IVE DEVICE Filed Dec. 51, 1941 6 Sheets-Sheet 6 fgldgreuure fm uexe/ 12 305 Patented June 27, 194

PRESSURE RESPONSIVE DEVICE Robert R. Donaldson, Forest Hills, Pa.Application December 31, 1941. Serial No. 425,166

Claims.

This invention relates to pressure sensitive devices for regulating andmetering varying operative conditions in a control system in accordancewith predetermined requirements and to methods bringing about suchregulation and metering.

One object of this invention is to provide method and apparatus forcontrolling the momentary values of interdependent operative conditionsin a manner that they satisfy the existing functional relationshipbetween them, as well as the requirements some other operative conditionimposes upon them in selectively variable dimensional magnitudes.

Another object is to provide method and apparatus of the characterdescribed which produce the controlled conditions in a steadilyprogressive, stable, practically non-oscillating manner, free from socalled hunting." Still another object is to provide method and apparatusfor controlling interdependent operative conditions affecting theirmeasurements in a selectively variable proportion, substantiallyaccording to a function of the tangent of an acute angle.

A further object is to provide method and apparatus for maintaining asubstantially constant flow of a fluid through a conduit when thepressure of the fluid and its resistance to flow may be subject tofluctuations and change, said flow to be selectively variable.

A still further object is to provide method and means for maintaining aselectively adjustable ratio or relationship between the flow of fluidsor gases or liqu ds in two or more different conduits.

Still a further object is to provide a pressure responsive apparatuswhich sends out pressure impulses of a compressed fluid in selectivelyvariable mathematical functional relationship to the pressures respondedto, said impulses remaining undisturbed by rocking or tilting of theapparatus.

Another object is to provide an apparatus of the kind mentioned which issimple in construction, sensitive. accurate and reliable in service andcan be adjusted to the characteristics of the individual controlsystems, in which it is utilized, during operation.

I achieve these and other objects by establishing forces, the magnitudeof which bear a predetermined functional relationship with the momentaryvalues of the conditions controlled, finding their resultant in asubstantially predetermined direction by loading these forces upon alinkage having a common oscillating pivot pin, employing control meansissuing an impulse pressure responsive to the position of this pin forvarying above mentioned forces, together with the values of therepresented conditions, until the resultant of all forces becomes zeroand the values of the conditions are the desired ones. Furthermore, byproper selection of the direction of the resultant, I am also able tovary at will the relative effectiveness, and with it select a desiredratio of the coordinated dimensional values, of the conditionsregulated.

Other objects of the invention will in part be obvious from thefollowing description taken in conjunction with the accompanyingdrawings in which:

Figure 1 is a diagram of the general arrangement of a control systememploying one preferred embodiment of my invention, the systemcomprising a pipe line for conducting a flowing fluid, said pipe linebeing provided with an orifice and a valve or damper operated by a fluidmotor which is controlled by a Pressure responsive device or pressureregulator to maintain a substantially constant pressure drop across theorifice, hence substantially constant intensity of flow of the fluidthrough said pipe.

Figure 2 is the diagram of a control system utilizing "asecondembodiment of my invention, this system comprising two separate pipelines through which fluids flow, each pipe line having an orificetherein; the intensity of the flow of one fluid in one pipe line beingvaried to satisfy certain requirements, a pressure responsive device orpressure regulator adapted to respond to the pressure drops across theorifices in the pipe lines and to control a fluid motor operated valveor damper in the other of said pipe lines so that the pressuredifferentials established across the two orifices and with it therespective intensities of the flow of the two fluids bear apredetermined but adjustable relationship to each other.

Figure 3 is the diagram of a control system based upon athird preferredembodiment of my invention, the system comprising a pipe line throughwhich a fluid flows, a valve therein positioned by a fluid motorcontrolled by a master regulator influenced by the momentary fluiddemand in the pipe line, an orifice and a regulator, responsive to thepressure drop thcreacross and at the same time to the electromagneticeffect of an electric current flowing through an electric prime mover,the load upon which'is in functional relationship with the intensity ofthe flow of the medium in said piping and said load being adjusted bysaid regulator to mainta n said functional selectively variablerelationship under varying fluid demand.

Figure 4 is an enlarged view of one preferred form of the inventedpressure responsive device or regulator provided with a variable ratiodevice and a dashpot, shown partially in section, parts being brokenaway, this regulator being used in the control system shown in Figure 1.

Figure 5 is an enlarged semi-diagrammat c elevational view of thedetached variable ratio device, an important structural feature employedin my invention, showing also the diagram of the acting forces.

Figure 6 is a view in section showing the details of construction, to alarger scale, of an escapement valve employed in the shown embodiments.

Figures 7 and 8 are more detailed views of the variable ratio deviceshown in Figure 5, in a modified arrangement.

Figure 9 is an enlarged sectional v ew of the chief structural elements,including the'variable ratio device and the dashpot, of the inventedregulator employed in the control'system shown in Figure 2.

Figure 10 is the enlarged sectional view of the invented regulator usedin the control system shown in Figure 3.

Figure 11 is a sectional view of a modified form of the inventedregulator serving as a metering device in which the dashpot is omittedand a cam containing loading device, operated by the control impulse, isemployed.

Throughout the drawings and specification like reference charactersindicate like parts.

Referring to the drawings I have shown in Figure 1, a pipe line I2through which a fluid. such as gas, air, or liquid flows in thedirection of the'arrow.

An orifice plate I4 is mounted in the pipe line whereby a pressuredifference (Pi-P2), as ind cated b pressure gauge I5, may be developedin accordance with or in response to the flow; P1 being the fluidpressure upstream from the orifice and P2 the pressure downstream fromit, either or both of which pressures may be variable.

If it is desirable to maintain a constant difference between pressuresP1 and P2. a damper or valve I6 is mounted in the pipe line I2 and sopositioned by means of an operator or fluid motor I8 that the differencebetween P1 and P2 and with it also the flow, as indicated by flow meterI1. remain substantially constant. Fluid motor I8 is controlled by aregulator embodying novel features of construction and arrangement ofparts so shown in more detail in Figure 4. "Regulator 20, connected bypipes 2I and 22 to pipe I2, responds to the differential pressure (P1P2)and is provided with a control element such as an escapement valve,generally designated by numeral 23, which governs the delivery of acontrol medium such as compressed air. to fluid motor I8 causing it toshift damper or valve I5 to positions that will maintain the intensityof the flow, hence the difference between varying pressures (P1P2)substantially constant. over the range of control of flow provided bythe damper or valve I6.

The fluid motor l8 may be of any approved type .but I prefer to use anoperator of the type shown and described in U. S. Patent No. 2,044,936

granted June 23, 1936.

As shown in Figure 4, regulator 20 comprises a box-like housing 24provided with a cover 26, a diaphragm 28, and sealing diaphragm 30.Diaphragm 28 divides the interior of the housing into a pressure tightchamber 32 which may be connected by pipe 22 to the downstream side oforifice I4, and a chamber 34 that may be connected by pipe 2I to theupstream side of orifice I4. Valve 23 and other hereafter describedstructural elements of the regulator are disposed within housing 24.

Diaphragm 28 is fastened at its periphery by a ring. 38 and a number ofscrews, to housing 24, and at its middle portion by plates 40 and acentral screw to a beam 42. Beam 42 is secured at 44 to the sealingdiaphragm 30 and to an arm 48 by a bolt 46, forming a bellcrankfulcrumed at 44. Sealing diaphragm 30 is fastened to housing 24 by meansof clamping ring 50 and suitable screws.

Escapement valve 23 comprises, as best shown in Figure 6, valve body 52having a cylindrical bore 54 provided with an inlet port 56 disposed toact as a valve seat for tapered surface 58 of a valve stem 50. A plug 62is threaded into valve body 52 and provided with a lock nut 64. Plug 62is provided with an exhaust port 66 coacting with a tapered surface 68on valve stem 88. A spring 18 urges stem against arm' 58 tending toclose exhaust port 66 to the atmosphere and to fully open inlet port 56to inlet duct 12 connected to piping I4, through whichcompressed airenters, as indicated by the arrow, from a suitable source (not shown) atconstant pressure, say 50 lbs. per square inch. Valve stem 68 ispositioned by arm 48 at all times and regulates the valv of controlimpulse' delivered through outlet 16 to an impulse sending line. Thevalue of pressure of the control impulse is a function I of the positionof surfaces 58 and 68 of valve stem 60 with respect to ports 56 and 66.The control impulse is conveyed in the direction of the arrows byimpulse sending line 18 to points of control such as fluid motor I8 andto a bellows chamber of dashpot 82; the bellows chamber being connectedby pipe 84 to impulse line 18.

Bellows chamber 80 accommodates a bellows 88 which is compressed by theimpulse pressure against the resistance of a spring 88 which tends tokeep the bellows in full expanded position. The space inside of bellows86 communicates with the cylindrical bore of dashpot 82 in which apiston 90 is reciprocably and adjustably mounted on a threaded pistonrod 92 which is suspended from a spring 96 and spring nuts 94 and 95.Spring nut 95 is threaded on forked bar 98 which is hingedly connectedto a variable ratio device, generall designated by numeral I00. Thisratio device represents an important structural feature of my invention.The dashpot 82 is provided with a needle valve I02 which adjustablycontrols the free area of by-pass port I04 connecting the space on bothsides of piston 88, which space contains a viscous fluid, such as oil. Adetailed description of the construction and operation of the dashpot inconnection with a regulator, is given in U. S. Patent No. 2,149,390,issued on March 7, 1939, for Pressure regulating device.

The variable ratio device I00, illustrated to a somewhat larger scale inFigure 5 which also shows the diagram of forces acting thereon,comprises three links I06, I08, and H0, hinged together by a common pinII2. For better reference, I call links I06 and I 08 the "componentlinks" and link IIO the "resultant link according to the forces actingprimarily thereupon. Component link I06 is hingedly connected to forkedbar 98 and also to spring II4 which is held to housing 24 with variabletension in the line of the axis of dashpot 82 by adjustable means, suchas eyebolt II6. Component link I08 is pivotally connected by pin II8 toarm 48 and is substantially perpendicular to link I06. Resultant link II has preferably one forked end to accommodate oscillating pin II2 andthe two component links, while its other end, of lesser width, ispivotally connected by pin I20 to a recessed end of post I22 protrudingfrom mounting member I24, shown to be a wormgear, mounted in housing 24rotatably and substantially coaxially with pin I I2 in latters middleposition. Positioning member I26, shown to be a worm, coacting withwormgear I24, is rotatably supported by housing 24 and is provided witha suitable knob I28 to be turned. Spring I30, adjustably tensioned byscrew I32, held in post I34 which is rigidly fixed to housing 24,balances substantially the turning moment of the pressures of spring I0and that of the compressed air transmitted by valve stem 60 upon arm 48,about fulcrum point 44 whereby it substantially eliminates the errorwhich would be otherwise caused by these pressures increasing the effectof Pi-P2.

Figures '7 and 8 show the variable ratio device I00 in more details,employing for mounting member I 24, a spur gear, and for positioningmember I26 a pinion, instead of wormgear and worm, respectively, shownin Figure 4, also the resultant link IIO being positioned in the upperquadrant to conform with the device shown in Figure 10.

The purpose of the apparatus shown in Figures l and 4 is to maintain aconstant pressure drop (say P) in the fluid flowing in pipe I2 throughthe orifice I4 and with it to keep the intensity of the flow of thefluid in the pipe constant (say I) in a manner that the controloperations should not cause fluctuations or hunting in the regulatedconditions. The described apparatus achieves this purpose in thefollowing manner:

Differential pressure Pl-P2 acts upon diaphragm 28 of the regulator 20,tending to turn counterclockwise about fulcrum 44, arm 48 which pulls oncomponent link I08 with a force F1 of a magnitude bearing a certainfunctional relationship with the momentary value of the pressure dropP1-P2, one of the interdependent conditions to be regulated. Graphicalrepresentation of the forces is shown in Figure 5. Accordingly, thenagnitude of force F1 is KC, that of Fzi-Fs is AB and that of theirresultant, R=Bc. The tension of spring II4 is so adjusted that it pullssubstantially perpendicularly to F1 upon ,component link I06 with aforce F2 of the magnitude bearing a certain functional relationship withthe intensity of the flow, the other of said conditions, plus offsettingthe weight bearing on pin II2. In line with F2 will act the stabilizingforce F3 of the dashpot, conveyed resiliently by springs 96 and bar 98,which force may be either in the same or in the opposite direction as F2in order to retard the effect of the variation of the force F1. In caseof equilibrium the stabilizing force already vanished, henceFabeequilibrium between the forces and the angles:

F2=R cos B+F1 cos A R=F1 cos C+F2 cos B F1=F2 cos A-i-R cos C and theratio of the component forces F2 and F1 iS F R cos B-l-F cos A F; F, cosA+R cost I prefer to arrange component links I06 and I08 substantiallyperpendicularly to each other in which case, with sufficiently closeapproximation, C= and F R cos B+F cos A C Fi Fg cos A+R cos C' an Theresultant of these component forces, which are substantiallyperpendicular to each other, is, with sufficient accuracy R=V 2+ and thereaction force, the stress developed in link IIO, will equal R1=R, linkIIO taking the line of the resultant that oscillates pin II2 about pinI20.

Disregarding the practically negligible difference in deviation of thecomponent links from the perpendicular to each other, (which differencecan be made very small by proper dimensions of the parts) in case ofequilibrium the sum of the forces By varying angle C between 0 and 90, Ican vary the ratio between forces F1 and F2 substantially between zeroand infinity, approximately according to a function of tangent C. Inother words, I can provide practically any ratio desired between forcesFiand F2 and find a position of equilibrium by simply turning knob I28and changing the value of angle C.

This variability of the ratio of the forces, meaning the variability ofthe effectiveness of the momentary values of the conditions, representedby said forces, makes possible, by positioning link IIO, to select atwill, during operation, the corrected value of the condition which is tobe maintained.

For example, in a particular case the proper intensity I is maintainedin pipe I2 when C=45 and P1P2=2" of water column. In this case, tg C=tan45=1 and F1=F2=2M lbs., where M is a factor, say .25, depending upon thesize of the diaphragm and the leverage, so that both F1 and F2=.25X2=.51b.

I wish now to regulate the flow pipe I2 so that the intensity shouldbecome I corresponding to 8" water column differential pressure(assuming that the dimensions of pipe I2 and valve I6 permil; suchincrease of the flow) To set the regulator to maintain this increaseddifferential pressure at orifice I4, angle C has to be adjusted so that(with sufficient approximation).

Hence. in this exemplary case, changing the angle C between center linesof links I08 and H from 45 to 11 2" will set regulator 20 to maintain inpipe- I2 a differential pressure of 8 water columninstead of 2 watercolumn'existing when C was 45". Any other practicable differentialpressure and corresponding flow intensity may be obtained by similarvariation of angle C, following substantially a tangent curve.

In general, regulator 20 functions as follows:

Assuming that during operation PiPz equals the desired P (as indicatedby a pressure gauge, I); hence the intensity of flow oi the fluid inpipe I2 is the desired I (as indicated'by a flow meter, I1) then nochange by the control apparatus is wanted and none is urged, as variableratio device I00 is in equilibrium. Diaphragm 28, arm 48, oscillatingpin H2, and accordingly, valve stem 60 also, will have a certainposition in response to which the control impulse in piping 18 has acorresponding pressure, positioning the piston of fluid motor l8 whichin turn keeps valve I8 set in the positionin which P differentialpressure was obtained at oriflce I4. As long as conditions P and Iremain, forces F1 and F2 do not vary, Fa=0 and the equilibrium of thevariable ratio device is not disturbed.

Assuming now, that due to opening or closing of some valves (not shown)above or below orifice I4, the pressures P1 or F2 or both, are changedand with them the intensity of flow too, and that the new difierentialpressure Pi-P2=P and the corresponding new flow intensity equals I. Thenif P' is greater than P, I will be greater than I and the followingchanges take place in the apparatus:

Diaphragm 28, loaded by the greater P tends to turn arm 48counterclockwise about fulcrum 44 which pulls now with a greater Fi'force upon component link I08, displacing oscillating pin II2counterclockwise about pin I20, lowering component link I08, increasingsomewhat (in this case practically negligibly) the tension of spring II4 which is force F2 until new resultant force R coincides with the newposition of resultant link I I0 at an angle C to F1. Asa result, valvestem 80 of escapement valve 23 will follow arm 48 under pressure ofspring and of the compressed air impinging upon the stem, opening upinlet port 58, and choking down exhaust port 88 in consequence of whichthe pressure 01 the control impulse in piping I8 will increase, movingthe piston of fluid motor I8 to position valve I8 to choke down the flowof fluid, simultaneously decreasing P accordingly. In the meantime, theincreased impulse pressure, conveyed by branch pipe 84 to bellowschamber 80, compresses bellows 86 and, through medium of the oil, whichcannot suddenly escape through the bypass port I04 in dashpot 82, movespiston 80 upwards compressing spring 88 and exerting an upward force +F3(increasing F2) that opposes F1 inasmuch it tends to shift oscillatingpin H2 and link IIO clockwise about pin I20. The effect of force F3 isthat link I08 arm 48, and valve stem 80 move toward right, decreasingthe pressure oi. the control impulse in piping I8 and slowing down themotion of the piston of fluid motor I8 and with it that 01' valve I8 andalso the speed of the correction of P and I toward the desired values ofP and I. The magnitude of force F2 is, however, decreasing due togradual relaxation of spring 98 on account of escaping oil fromunderneath to above the piston 80 through port I04, so that within atime period, depending upon adjustment of needle valve I02, F3 becomeszero.

To prevent overtravel of fluid motor I8 and valve I8, henceavoi'dhunting, it is necessary that valve I8 arrive at the properchoking position in which it reduces P to P andI to I substantially atthe momentwhen Ft becomes uro, otherwise this varying-force would causevarying-F1 and F2 forces and would prevent equilibrium at pin II2 of thevariable ratio device I00; this would mean continued positioning offluid motor I8 and of valve I 8 constituting overtravel and hunting. Thecorrelation oi the speed of cor-.

rection 01 P and of the time period within which Fa, the stabilizingforce, becomes zero, is achieved by proper setting of needle valve I02and suitable selection of the active number of turns of spring 88 bysetting spring nuts 84 and 85.

Selecting the proper angle C by observing pressure gauge I5 and/or flowmeter I1, the regulator is set to maintain the properly corrected values01' the interdependent conditions of the pressure difference Pi-P: andthe intensity 0! the flow I, as above explained.

In case the momentary value of P1P: becomes P" which is less than P,then force F1 decreases to F1", diaphragm 28, arm 48, link I00,oscillating pin H2, and valve stem will be shifted to the right, linkI08 liited, spring II4 slightly relaxed, iorce F: somewhat decreased toF2 and the pressure of the control impulse also decreased. Inconsequence, fluid motor I8 is started to open further valve I8 forincreasing P" toward the desired P. In the meantime, bellows 88, underpressure of spring 88, expands, suck piston 00 downwardly, tensioningspring 88 and exerting a force F3" which opposes force F1" as the formertends to move II2 to the left and the latter to the right. The result isagain that the motion of valve I8 and the correction of P" to P isretarded sufliciently so that the desired diil'erential pressure P isreached at the moment when F3" becomes zero, hence, equilibrium at pinH2 and with it P and I is reestablished progressively without overtraveland hunting.

Fig. 9 shows a second embodiment of the regulator, generally designatedby I30, which is used in the arrangement illustrated in Fig.2;

In this control system, a fluid, say fuel gas,

from a known master sender I32, conveyed through piping I34, in responseto a master impulse. say the pressure of the generated steam, reachingmaster sender I32 through piping I38. The pressure drop P3P4 and thecorresponding flow intensity 11 in piping I38 is so regulated by valveI8 that it satisfies the momentary fuel requirement as determined by thesteam demand and corresponding steam pressure. variation. Another fluid,say air, necessary for the combustion of the fuel gas, is flowing inpipe I2 in the direction of the arrow through orifice I4, the pressuredrop P1-P2 through which is regulated by damper or valve I8 positionedby fluid motor I8 controlled by regulator I80, so that the correspondingintensity of flow 12 in pipe I2 is in a predeterm ned proportion K tointensity I1 in pipe I38. Hence,

I5 and I5 are diflerential pressure gauges, and I1 and I1 flowmeters.

As shown in Fig. 9, regulator I30 comprises boxlike housing I42, shownbroken away, which accommodates the parts described in connection withregulator 20 in Fig. 4, except spring H4, and the following newstructures:

Cover I44 with diaphragm I46 and sealing diaphragm I48 form the sealedchambers I50 and I52, the former being connected through piping I54 withpipe I38 downstream to orifice I40, and latter, through piping I56,upstream to orifice I40, so that chamber I50 is under the lower pressureP4 and chamber I52 under the higher pressure P; at all times. Thediaphragms are fastened sealingly to housing I42 in the usual manner byperipheral rings I58 and I60, while at their center they are attached tobeam I62 which is rigidly bolted to arm I64 forming a bell-crankfulcrumed at the center I66 of sealing diaphragm I48. Component link I06of the variable ratio device I is pivotally suspended at pin I68 fromarm I64. Spring I12, .adjustably tensioned by screw I14 in post I 16,which is rigidly attached to housing I42, balances the weight of theparts resting on oscillating pin II2.

This regulator operates in the same manner as regulator 20 shown in Fig.4, except that the force F1,-due to the momentary differential pressurePlP2, respectively to the corresponding flow intensity I2, is balancedat pin I I2 by a force F: which is in functional relationship with thedifferential pressure P3P4, respectively with its interdependentintensity of flow 11. The angular position of resultant link IIO tocomponent link I08 or the magnitude of angle C will determine the ratiobetween the balancing forces F1, F2, and also that of the flowintensities I1 and I2.

Resultant link H0 is positioned and angle C varied by wormgear I24 andworm I26, rotatably held in housing I42, gear I24 being coaxial withfloating pin II2 at the latters middle position. The position of valvestem 60 of escapement valve 23, hence also the pressure of the controlimpulse in piping 18 and with it the position of the piston of fluidmotor I8 and that of the valve I6, are determined by the position of theoscillating pin II2. is obtained between forces F1, F2, and R1 at pinII2the stabilizing force F3 becoming zeroI3 becomes M1, the desiredvalue, and any further correction, overtravel or hunting is eliminated.

Any desired ratio between the intensities of the flow of the twodifferent fluids, respectively any value of k=f (tan C) (substantially)may be obtained by setting resultant link H0 at the proper angle C byturning knob I28 that positions worm I26 and gear I24. It is obviousthat the described apparatus can regulate the proportional flow not onlybetween fuel and air but between different kind of fuels or between anykind of fluids whatsoever.

Fig. 10 shows the third embodiment of the invented regulator, generallydesignated by I18, used in the control system shown in Fig. 3. In thissystem air, carrying pulverized coal, is driven by fan I60 in pipe I2 inthe direction of the arrow, toward burners of a steam boiler (notshown). Damper or valve I6, positioned in pipe I2 by fluid motor I8according to the control impulse received through piping I34 from mastercontrol I32 in response to the steam pressure variation conveyed bypiping I36, regulates the pressure drop P1P2 at orifice I4 so that thecorresponding intensity of flow should satisfy the momentary fuel demandas required by the steam load, indicated by the variation of the steamConsequently, at the moment equilibrium pressure. The coal is pulverizedby a mill I82 of suitable type which grinds the coal furnished by feederI84, driven at proper speed by electric motor I86, the speed of whichmotor can be varied by rheostat I88, positioned by fluid motor I8, inresponse to the control impulse received through piping 18 from theregulator generally designated by the numeral I18. Fan I sucks throughmill I82 the air that picks up the pulverized coal and carries it awaysuspended therein. Fan I80 and mill I82 are driven by electric motorI90, which, together with motor I86 receive the necessary electriccurrent through electric leads I92 at the pressure E volts from asuitable outside-source, not shown. A current transformer I94, inelectric contact with leads I92, is connected by conductors I96 tosolenoid coil I98 in regulator I18 as shown in Fig. 10.

Regulator I18 comprises boxlike housing 200 which accommodates withlittle exception, the same parts as regulator 20, though some of themare somewhat difierently shaped and besides these, it contains alsosolenoid coil I98 and the magnetic core 202 adjustably attached by setscrew 204 to bar 98 which connects link I06 to spring 96 of dashpot 82.Instead of spring II4 of Fig. 4, supplying there a force F2, here aspring 206 is employed for balancing the weight upon pin II2 and is heldwith adjustable tension in a spring shield 205 by spring nut 208 andthreaded bar 2I0 positioned by thumb nut 2I2 for regulating the tensionof the spring to balance the weight exactly. Spur gear I24 carryingpivotally resultant link H0, is rotatably mounted in housing 200,substantially coaxially with the middle position of pin II2; pinion I26,turnable by knob I28, is held in cooperative position with spur gearI24. As force F2 here is exerted by electromagnetic attraction betweensolenoid coil I98 and magnetic core 202, acting downwardly from pin II2,escapement valve 23 is in reversed position and resultant link H0 isplaced in an upper quadrant of gear 124 to accomplish the correspondingdisplacement of valve stem 60 in an opposite direction to that oneexecuted by regulator 20, in Fig. 4.*Forthis purpose arm 48 is providedwith an extension 2 carrying adjusting screw 2"; locked thereto, whichscrew contacts and positions valve stem 60 in accordance with theposition of oscillating pin II2. Beam 42, fastened to arm 48 by bolt 46forming a bellcrank with fulcrum point at 44, indicated by a smallcircle in Fig. 10 in the center of sealing diaphragm 30, is providedwith a counterweight 2l8 of suitable dimensions to bring the center ofgravity of the swinging parts 28, 40, 42, 46, and 48 into the fulcrumpoint 44 in order to eliminate any gravitational moment which would varywith the different positions of these parts and would cause an error inthe regulation by influencing the magnitude of the force F1. It isobvious that this balancing of the pivoting parts maybe effected inevery embodiment of my invention. This feature has particular importancein diaphragm operated apparatuses used in moving structures such asships, airplanes, motor vehicles, etc., exposed to rocking and tilting.

The variable ratio device I00, in which the resultant link I I0 isarranged in an upper quadrant and force F: acts downwardly from floatingpin II2, is. shown in greater detail to a larger scale in Figs. 7 and 8,in which, for the sake of simplicity, spring 206 is shown to be heldadjustably by eyebolt IIB to housing 200.

The apparatus shown in Figs. 3 and functions as follows:

The differential pressure P1P2 is varied by master sender I32 inresponse to the steam demand on the boiler, not shown, determining themomentary requirement of powdered coal and air and with it the necessarymomentary intensity of flow in pipe I2. The pressure drop P1P2 causesthe pulling force F1 on component link I08 in the direction to the leftfrom the oscillating pin II2 moving the pin II2 toward the left andclockwise about the pin I20. The intensity of the flow of air and withit the quantity of pulverized coal carried by it (the output of themill) is in functional relationship with the pressure drop Pi- P:; andso will be the rate of feed of necessary coal corresponding to thisoutput determining the momentary power requirement of motor I90, hencethe intensity or amperage of the consumed electric current and themagnitude of the developedforce F2.

Assuming that the intensity of the air flow in pipe I2 and thepulverized coal carried thereby satisfy the momentary fuel requirementof the load on the boiler, then motor I86 is driving coal feeder I64with the correct speed delivering coal to the grinding mill I82 at thenecessary rate to maintain the proper pulverized coal content of the airat that flow intensity. In such case motor I90 requires a certainintensity of current flowing through leads I92 which will induce acorresponding current say of S-amperes in cur-- rent transformer I94activating solenoid coil I98 which will pull on magnetic core 202 and onlink I06 connected thereto with a force F: that balances force F1 atfloating pin H2 at the established position of resultant link IIO.

Should the load on the boiler increase and the steam pressure in pipeI36 fall, master sender I32 issues an impulse opening further valve I6causing an increase in the momentary value of P1P2, hence, in that offorce F1 acting on component link I08. In consequence, floating pin II2will move toward the left and clockwise about pin I; valve stem 60 willmove also to the left but in this reversed position toward its inletport, choking it down, decreasing the pressure of the control impulseentering piping l8 and setting the piston of fluid motor I8 into motionto start rheostat I88 toward a position in which the speed of motor I86would deliver coal to mill I82 at the higher rate corresponding to theincreased intensity of air flow answering the increased fuel demand. Thedecreased pressure of the control impulse in piping I8 is conveyedthrough piping 84 to bellows 86 in bellows chamber 80 causing a downwardforce F: of gradually vanishing magnitude opposing the effect of forceF1. Mill I82 being of suitable type, the increase in the rate of coalfeed increases the power requirements of motor I90, hence, also theamperage S in solenoid I98 and with it the electromagnetic attraction oncore 202, supplying force F2.

As in the previously described embodiments in connection with Figs. 4and 9, force Fa retards the positioning of the piston of fluid motor I8and with it th aimed at setting of rheostat I88 so that the resultant ofall forces acting on floating pin II2 becomes zero and equilibrium atthe variable ratio device I00 is established between forces F1(corresponding to the new, greater magnitude of Pi-P: as set by themaster sender I32) and F2 (corresponding to the increased rate of coalfeed and to the resulting greater amperage S as set by fluid motor I8and rheostat I88 in response to the decreased pressure of the controlimpulse in piping 18) substantially at the same instant when force 1*;becomes zero.

Should the load on the boiler now increase, the regulator effectssimilar steps of control in the opposite direction to that previouslydescribed resulting again in continuous, progressive and quickregulation of the conditions to be corrected establishing the propercorrelated values of momentary fuel demand and pulverized coal output ofthe grinding mill without overtravel and hunting.

Suitably positioning resultant link H0 in the described manner, byvarying angle C, any ratio may be obtained between intensity of airflowor the necessary fuel requirement and the rate of feedng coal into thepulverizing mill, hence the proportion of the pulverized coal to thecarrying air can be varied at will between practical limits, insuringmost economical operation with coals of varying fuel values. Again, theratio between the regulated conditions may be varied according to afunction of the tangent of the acute angle C by varying the angularposition of link IIO.

Fig. 11 shows a modification of the invented regulator, generallydesignated by 220, serving as a metering device and issuing controlimpulses of compressed fluid, the pressure of which impulses 'bears apredetermined functional relationship to the momentary value of themeasured condition.

This regulator comprises boxlike housing 222 containing, with theexception of the dashpot and the parts therein, the same structures asregulator 20 in Fig. 4, and in addition thereto a second pressureresponsive device 224 and a cam 226 operated bellcrank 228, tensioningspring II4.

Omitting the description of the parts common with the previouslydisclosed embodiments and referred to by the same numerals, the newparts employed in this embodiment are:

Diaphragm 230, forming with cover 232 the sealed chamber 234 into whichthe control impulse from escapement valve 23 is conducted and from whichthe outgoing impulse issues, as shown by dotted arrows. Diaphragm seat236 and post 228 clamp the central portion of diaphragm 230 andposition, against the pressure Fe of suitably dimensioned spring 240,cam 226 which is pivotally mounted by screw 242 in housing 222. Post 296is provided with ball-joint 244 and forked end 246 which is linked tocam 226 by screw 248 permltting oscillation of the cam about screw 242.Roller 250 is rotatably mounted on 'bellcrank 228 which is pivotingabout screw 252 and has a forked pivoting arm 254 adjustably attachedthereto by locked screw 256. Forked arm 254 has pin 258 which engagesextension spring H4 and tensions it with a force Ft pulling on componentlink I06. All pivoting parts are preferably provided with antifrictionbearings not shown.

Face 260 of cam 226 is shapedto form a profile which will positionbellorank 228 and pin 268 relative to diaphragm 230 so that forces Feand Ft are in a predetermined functional relationship with each other,hence,

The diaphragm 28 is subjected to the d fferential pressure Pl-P2 at anorifice, not shown. As previously explained F1=M (Pl-P2) where M is aconstant factor and hence, Ft=Fl tan C'=M(P1P2) tan 0 and Fc=f[M(P1P2)tan C].

Inasmuch as the pressure of the outgoing impulse Pi multiplied by theeffective area A of diaphragm 230 balances the pressure Fe and themoment bFt of the tension Ft (b being a suitable factor depending uponthe dimensions of the parts) In other words the pressure of the controlimpulse issued from this regulator will bear a functional relationshipto the measured pressure difference, the function being predeterminedaccording to the selected profile of the face of the cam 226 and havingtan C as independent variable. Varying angle C by positioning resultantlink in turning knob I28 and with it worm I26 and gear I24, an infinitenumber of values of the predetermined" functional relationship betweenobserved differential pressure and issuing control impulse can beobtained substantially according to the variation of the tangent of anacute angle.

It is obvious that by proper selection of springs 240 and Ill and of theprofile 260 of cam 226, any observed variation of pressure may beexpressed in terms of acting pressure or force according to any desiredfunction in which tan C is an independent variable; and not only canthis be utilized to operat known indicators or recorders but any desiredcontrolor other work' can be accomplished in cooperation with amultitude of known pressure utilizing devices responsive to the impulsepressure of this regulator, respectively metering device.

While I have fully disclosed my invention and explained its operationwith reference to preferred embodiments, it will be understood thatthese serve as illustrative examples only and should not be construed aslimitations of my invention which should be limited only by the priorart and the appended claims.

What I claim as new and desire to secure by Letters Patent is:

l. A control device for regulating interdependent variable conditions toassume selectively variable values satisfying the requirements imposedby some other condition, said device comprising an oscillatably mountedpin and two component links and one resultant link pivotally mounted onsaid osciliatably mounted pin, loading means for exerting upon saidcomponent links forces characteristic of and bearing predeterminedfunctional relationship to the momentary values of said interdependentconditions, said loading means exerting forces which pull saidcomponent.

links away from, and in a. perpendicular direction to the axis of saidpin, pressure responsive stabilizer means for adding a temporaryretarding force of diminishing value to said forces, a supporting membermounted rotatably and substantially coaxially with said pin at itsmiddle position, said resultant link being pivotally mounted on saidsupportin member, positioning means for changing the angular position ofsaid supporting member and that of said resultant link for varying theratio of the balancing magnitudes of said forces, a source of supply offluid medium control means actuated in accordance with changes in theposition of said oscillating pin for delivering and controlling thevalue of pressure at which said pressure medium is delivered 1| to saidstabilizer means, the value of pressure delivered to said stabilizermeans becoming steady when the forces exerted on said pin by and throughsaid component and resultant links are in balance.

2. A control device for regulating interdependent variable conditions toassume selectively variable values satisfying the requirements imposedby some other condition, said device comprising an oscillatably mountedpin and two component links and one resultant link pivotally mounted onsaid oscillatably mounted pin, loading means for exerting upon saidcomponent links forces characteristic of and bearing predeterminedfunctional relationship to the momentary values of said interdependentconditions, pulling said component links away from, and in a.perpendicular direction to the axis of said pin, and also substantiallyperpendicular to each other, pressure responsive stabilizer means foradding a temporary retarding force of diminishing value to said forces,a. supporting member mounted rotatably and substantially coaxially withsaid pin at its middle position, said resultant link being pivotallymounted on said supporting member, positioning means for changing theangular position of said supporting member and that of said resultantlink for varying the ratio of the balancing magnitudes of said forcessubstantially according to the variation of the tangent of the acuteangle formed by one of said forces with said resultant link, a sourc ofsupply of fluid medium under pressure, and control means actuated inaccordance with changes in the position of said oscillating pin fordelivering and controlling the value of pressure at which said pressuremedium is delivered to said stabilizer means, the value of pressuredelivered to said stabilizer means becoming steady when the forcesexerted on said pin by and through said component and resultant linksare in balance.

3. Control apparatus according to claim 2 in which said loading meanscomprise a fluid pressure responsive device exerting force upon one ofsaid component links, the magnitude of said force being in functionalrelationship with the momentary value of the pressure drop in a fluidflowing in a vessel through a resistance such as an orifice, and aspring connected to and exerting a force upon the other of saidcomponent links, the magnitude of which last mentioned force opposingthe force exerted by said pressure responsive device and in proportionto the displacement thereof by said pressure drop.

4. Control apparatus according to claim 2 in which said loading meanscomprise two fluid pressure responsive devices, each exerting pullrespectively upon one of said component links, the magnitude of saidpulls being in functional relationship with the momentary values of saidinterdependent conditions, said stabilizing means comprising a dashpothaving a piston reciprocably accommodated therein and resilientlyattached to one of said component links for displacing a fluid, such asoil, through an adjustable bypass in response to a pressur impulseacting upon said fluid, and said source is one supplying compressed airat constant pressure, and said control means comprising an escapementvalve regulating the pressure of the issuing impulse of said compressedair, said impulse acting upon said dashpot.

5. Control apparatus according to claim 2 in which said loading meanscomprise a pressure differential responsive device operatively connectedto one of said component links and'to exert a force on said pin thatvaries with the pressure differential acting on said pressuredifferential responsive device, and an electric current responsivedevice having a coil disposed to be energized by electric current and anarmature operatively connected by the other component link to saidoscillatably mounted pin and disposed to exert a force thereon tendingto turn said resultant link, the force exerted by said armature varyingwith the value of current in said coil, said stabilizing meanscomprising a dashpot, with a piston reciprocably mounted therein, meansresiliently connecting said piston to one of said component links fordisplacing a fluid, such as oil, through an adjustable bypass inresponse to a pressure impulse acting upon said fluid, and said sourceis one supplying compressed air at constant pressure, and said controlmeans comprises an escapement valve operatively connected to said linksfor transmitting a control pressure the value of which varies inaccordance with the displacement of said oscillatably mounted pin ascaused by the sum total of forces acting thereon.

6. In a control apparatus, for comparing momentary values ofinterdependent conditions at a selected ratio of effectiveness, avariable ratio device comprising a pin, and two component links mountedsubstantially at a right angle to each other and a resultant link, eachof said component links being pivotally connected to said pin, said pinbeing carried by said resultantlink, a mounting member substantiallycoaxially rotatably arranged as to said pin at its middle position,means to attach said resultant link pivotally to said member, means forrotating said mounting member and turning said resultant link about saidpin, loading means connected'to said component links for exerting forcesthereon the magnitude of each of which bears a predetermined functionalrelationship to the value of one of said interdependent conditions, andfluid pressure control means disposed for operation by said loadingmeans and links in accordance with the displacement of said pin, saidfluid pressure control means delivering a fluid pressure control forcethat varies in magnitude in accordance with said pin displacement.

7. A variable ratio device according to claim 6 in which said loadingmeans comprise a first fluid pressure responsivedevice connected to oneof said component links and being influenced by v the momentary value ofone of said conditions and a second fluid pressure responsive deviceacted upon by said fluid pressure control force, and a cam mechanismoperatively and resiliently connecting another of said component linksand said second fluid pressure responsive device the working face ofwhich cam mechanism is suitably shaped to establish the desiredfunctional relationship between the momentary value of a condition andthat of said fluid pressure control force.

8. A regulator for correcting in a pipe line the intensity of the flowof fluid and its differential pressure at an orifice to assumesubstantially without fluctuation, selectively variable values to bemaintained, said regulator comprising a pin and two component links andone resultant link, said pin forming one common pivotal connectionbetween said component and resultant links, a rotatably mounted supportmember for said resultant link, the axis of said support member beingsubstantially coaxial with said pin when the pin is in its middleposition, means to attach said resultant link pivotally to said supportmember, means for rotating said member and thereby turning saidresultant link about said pin, an airtight chamber having therein adiaphragm responsive to said differential pressure, a lever connected toone of said component links and to said diaphragm, an adjustablytensioned spring connected to the other of said component 4 links insubstantially perpendicular direction to the first component link, asource of supply of compressed air at constant pressure, an escapementvalve connected to said source and operatively connected to said leverfor issuing control impulses from said source at pressures that varywith the displacement of said pin by the action of said diaphragm andspring on said component and resultant links, and a dashpot having apiston and a displaceable liquid therein, means resiliently connectingthe piston to one of said component links, said dashpot exerting astabilizing force through its spring and component link on said pin.

9. A regulator for correcting in a pipe line having' an orifice therein,the intensity of the flow of fluid and its difierential pressure at saidorifice to assume substantially without fluctuation, values ofselectively variable proportionality with respect to the intensity ofthe flow of another fluid in another pipe line having an orificetherein, said regulator comprising a pin, two component links, and oneresultant link, said pin connecting said links and forming one commonpivot point therefor, a rotatably supported mounting member for saidresultant link, said resultant link being pivotally secured to saidmounting member and so positioned that the pin is substantially coaxialwith the axis of said mounting member, means for turning said mountingmember whereby said resultant link is turned about said pin, twodiaphragms, a pressure tight chamber for each diaphragm, one of whichdiaphragms is responsive to the pressure differential across the orificein one of said pipes, and the other diaphragm being responsive to thepressure difierential across the other of said orifices, a bellcrank foreach diaphragm for operatively connecting the same to said componentlinks, a sealing diaphragm for each chamber, said bellcranks beingfulcrumed on said sealing diaphragm and exerting forces on saidcomponent links in substantially perpendicular direction to each other,a source of supply of compressed air at constant pressure, an escapementvalve coacting with one of said bellcranks for issuing a control impulsefrom said source at pressures that vary with the displacement of saidpin by the action of said diaphragms and links, and a dashpot having acylinder and a. piston reciprocably accommodated therein, means forresiliently connecting said piston to one of said component links, arestricted by-pass communicating with said cylinder at opposite sides ofthe piston, liquid in said cylinder, and means responsive to thepressures issuing from said escapement valve for displacing said liquidto thereby exert a displacing 'force on said piston, said displacingforce being gradually diminished and dissipated and two component linksand one resultant link, said pin connecting said links and forming onecommon pivot point therefor, a rotatably supported mounting member forsaid resultant link, means for rotatably securing said resultant link tosaid mounting member, said resultant being so positioned that the pin issubstantially coaxial with the axis of said mounting member, means forturning said mounting member, an airtight chamber having a diaphragmtherein responsive to a differential pressure across the orifice in saidpipe line, a sealing diaphragm for said chamber, a bellcrank fulcrumedon said sealing diaphragm and to one of said component links and to saidpressure diflerential diaphragm, an electromagnetic device responsive tothe load current on said mill motor and connected to said secondcomponent link for exerting a force thereon in substantiallyperpendicular direction to the first component link, the force of saidelectromagnetic device being proportional to the load on the mill motor,an adjustably tensioned spring supporting -the weight acting upon saidpin, a. source of supply of compressed air at constant pressure, anescapement valve coacting with said bellcrank for issuing a controlimpulse from said source at a pressure correlated with the position ofsaid pin, anda dashpot having fluid therein and a piston reciprocablyaccommodated therein, means resiliently connecting said piston to otherof said component links for displacing said fluid, an adustablerestricted by-pass associated with said dashpot, means responsive tosaid control impulse and acting to displace said fluid, thereby exertinga force on said piston that gradually diminishes and is dissipated insaid by-pass, and means responsive to said control impulse forregulating the rate of feed of coal into said mill.

ROBERT R. DONALDSON.

